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Pool chlorinators eliminate the daily chore of manually measuring and adding chlorine to a swimming pool. Consisting of a canister installed directly into the pool water return line after the filter, or in a bypass loop that diverts a small flow of pressurized water from the pump around the filter and back to the return line, a chlorinator meters the flow of water over chlorine tablets or sticks that gradually dissolve. Typically, the canister contains about 9 pounds of chlorine, sufficient to chlorinate a residential pool for around two weeks before refilling is required. With few moving parts and only a single manual adjustment, most problems with pool chlorinators are limited to water flow issues.

Installation Errors

Dissolving the chlorine tablets relies on water flowing in the correct direction through the canister. A bypass chlorinator takes water from a "T" fitting immediately after the pump and conveys it through a hose to an injection fitting in the chlorine canister. Chlorinated water leaves the canister in a hose that connects to the main return line after the filter. If the chlorinator was inadvertently installed with these hoses reversed, the injection process that dissolves the chlorine will not function. Arrows on the side of most chlorinators indicate the proper direction of water flow through the hoses.

Obstructed Water Flow

The injection fitting where the inlet line connects to the canister contains very small water jets that may clog with debris, preventing sufficient water flow to dissolve the chlorine. Inserting the bent end of a paper clip into the jets to clear the blockage may restore water flow. An accumulation of calcium and other hard water deposits inside the canister can restrict circulation in and out of the canister and contribute to slow-dissolving tablets.

Air Locks

Air that has entered the system elsewhere, usually through a leaky O-ring in the pump, may be trapped in the chlorinator canister and cause an air lock. This will become evident by unscrewing the canister lid with the pool pump turned off. A very low water level in the canister indicates the presence of air. Restarting the pump with the lid removed and allowing the canister to fill with water and purge the air may restore flow through the system. After the canister fills with water, the lid should be reinstalled.

Improper Adjustment

The flow of water into the canister is controlled by a dial on the top or side of the chlorinator. Turning up the water flow dissolves the tablets faster, increasing the concentration of chlorine in the pool. If the chlorine dissolves too slowly to adequately chlorinate the pool, turning the adjustment dial to a higher water flow may alleviate the problem.

About the Author

Gus Stephens has written about aviation, automotive and home technology for 15 years. His articles have appeared in major print outlets such as "Popular Mechanics" and "Invention & Technology." Along the way, Gus earned a Bachelor of Arts in communications. If it flies, drives or just sits on your desk and blinks, he's probably fixed it.